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Home My WebLink AboutWILLOX FARM - FDP240005 - SUBMITTAL DOCUMENTS - ROUND 1 - Geotechnical (Soils) ReportPRELIMINARY SUBSURFACE EXPLORATION REPORT PROPOSED RESIDENTIAL DEVELOPMENT WILLOX FARM - APPROXIMATELY 19.3-ACRES SOUTH OF WILLOX LANE AND ½-MILE WEST OF COLLEGE AVENUE FORT COLLINS, COLORADO EEC PROJECT NO. 1212027 Prepared for: Mosaic Land Development Services, LLC 1021 Nightingale Drive Fort Collins, Colorado 80525 Attn: Mr. Andrew Hartsel (a.hartsel@developmentbymosaic.com) Prepared by: Earth Engineering Consultants, LLC 4396 Greenfield Drive Windsor, Colorado 80550 4396 GREENFIELD DRIVE W INDSOR, COLORADO 80550 (970) 545-3908 FAX (970) 663-0282 May 6, 2021 Mosaic Land Development Services, LLC 1021 Nightingale Drive Fort Collins, Colorado 80525 Attn: Mr. Andrew Hartsel (a.hartsel@developmentbymosaic.com) Re: Preliminary Subsurface Exploration Report Proposed Residential Development – Willox Farm (Larimer County Parcel #970220003) Approximately 19.3-Acres – South of Willox Lane and ½-Mile West of College Avenue Fort Collins, Colorado EEC Project No. 1212027 Mr. Hartsel: Enclosed, herewith, are the results of the preliminary subsurface exploration completed by Earth Engineering Consultants, LLC personnel for the referenced project. A total of seven (7) preliminary soil borings were drilled on April 21, 2021, at the approximate locations as indicated on the enclosed Boring Location Diagrams included with this report. The borings were extended to depths of approximately 12 to 25 feet below existing site grades. Individual boring logs, including groundwater observations, depth to bedrock, and results of laboratory testing are included as a part of the attached report. This exploration was completed in general accordance with our proposal dated February 19, 2021. In summary, the subsurface soils encountered in the preliminary test borings generally consisted of a relative shallow depth of overburden slightly cohesive subsoils underlain by a zone of fine to coarse granular subsoils, which extended to the bedrock formation below. Clayey sand, silty, clayey sand and/or sandy lean clay subsoils were encountered in each of the preliminary borings beneath the surficial topsoil/vegetative layer and extended to depths of approximately 3 to 5 feet below existing site grades. Silty sand with gravel with interbedded cobbles at increased depths, was encountered beneath the upper slightly cohesive zone and extended to the bedrock formation below in all borings except for Boring B-3. Auguer refusal was encountered in Boring B-3 within a very dense granular/cobble zone at a depth of approximately 12-1/2 feet below existing site grades. Siltstone/sandstone/claystone bedrock was encountered at depths of approximately 16 to 18 feet below existing site grades and extended to the depths explored. The upper slightly cohesive subsoils were generally dry to moist in-situ, soft to stiff / loose to medium dense, exhibited low to moderate plasticity and low swell potential at current moisture and density conditions. The granular zone was moist to wet, Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 2 medium dense to dense and exhibited moderate bearing capacity characteristics. The bedrock formation was generally weathered near surface, becoming moderately hard to hard and/or poorly cemented to cemented with increased depths. At the time of drilling and when checked after the completion of the drilling operations, groundwater was observed in the borings at relatively shallow depths of approximately 3 to 5 feet below existing ground surface elevations. Based on the materials observed within the preliminary boring locations and the anticipated foundation loads, we believe the proposed lightly loaded, single-story to 2-story residential structures, having slab- on-grade, crawl-space, garden-level, and/or full-depth construction could be supported on conventional type spread footings bearing on native subsoils or on a zone of engineered/controlled fill material placed and compacted as described within this report. Due to the variable depth to groundwater across the site and the possibility of ground modifications to achieve stable bearing conditions at various locations, consideration could be given to supporting the residential structures on a grade beam and straight shaft drilled pier foundation system extending into the underlying bedrock formation. Groundwater was encountered across the site within the preliminary borings at approximate depths of 3 to 5 feet below existing site grades. If lower level construction or full-depth basements are being considered for the site, we would suggest that the lower level subgrade(s) be placed a minimum of 4 feet above the maximum anticipated rise in groundwater levels, or a combination exterior and interior perimeter drainage system(s) be installed. Also, consideration could be given to 1) either designing and installing an area wide underdrain system to lower the groundwater levels provided a gravity discharge point can be established, (if a gravity outlet/system cannot be designed another consideration would be to design and install a mechanical sump pump system to discharge the collected groundwater within the underdrain system, or 2) elevate/raise the site grades to establish the minimum required 4- foot separation to the maximum anticipated rise in groundwater. Additional drainage system recommendations are provided within the text portion of this report. In general, it appears the in-situ site materials could be used for support of interior slab-on-grades, exterior flatwork, and site pavements; however, ground modification procedures, such as over- excavation and replacement of existing fill materials as approved engineered fill and placement of an approved imported fill material may be required to reduce post-construction movement. Post- construction movement cannot be eliminated. Additionally, the cohesive subsoil materials may be subject to strength loss and instability when wetted. Close monitoring and evaluation during the construction phase should be performed to reduce post-construction movement. PRELIMINARY SUBSURFACE EXPLORATION REPORT PROPOSED RESIDENTIAL DEVELOPMENT WILLOX FARM - APPROXIMATELY 19.3-ACRES SOUTH OF WILLOX LANE AND ½-MILE WEST OF NORTH COLLEGE AVENUE FORT COLLINS, COLORADO EEC PROJECT NO. 1212027 May 6, 2021 INTRODUCTION The preliminary subsurface exploration for the proposed approximately 19.3-acre residential development property located south of Willox Lane and approximately ½-mile west of North College Avenue in Fort Collins, Colorado has been completed. A total of seven (7) soil borings were drilled on April 21, 2021 at the approximate locations as indicated on the enclosed Boring Location Diagrams included with this report. The preliminary soil borings were advanced to depths of approximately 12-1/2 to 25 feet below existing site grades across the proposed development property to obtain information on existing subsurface conditions. Auger refusal was encountered within a very dense granular/cobble zone in Boring B-3 at a depth of approximately 12-1/2 feet. Individual boring logs and site diagrams indicating the approximate boring locations are included with this report. The property, as we understand, will be developed for approximately 71 single-family residential lots including utilities and interior roadway infrastructure. Foundation loads for the proposed residential development structures are anticipated to be light to moderate with continuous wall loads less than 4 kips per lineal foot and individual column loads less than 150 kips. Floor loads are expected to be light. Proposed residential structures are expected to include possible below grade construction such as crawl spaces, garden-level and/or full-depth basements. We anticipate maximum cuts and fills on the order of 5 feet (+/-) will be completed to develop the site grades. Overall site development will include construction of interior roadways designed in general accordance with Larimer County Urban Area Street Standards (LCUASS) Pavement Design Criteria. The purpose of this report is to describe the subsurface conditions encountered in the preliminary borings, analyze and evaluate the test data and provide preliminary geotechnical recommendations concerning site development including foundations, floor slabs, pavement sections and the possibility for an area underdrain system to support basement construction. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 2 EXPLORATION AND TESTING PROCEDURES The boring locations were established in the field by a representative of Earth Engineering Consultants, LLC (EEC) by pacing and estimating angles from identifiable site features. Approximate ground surface elevations were extrapolated from Google Earth and are recorded on each boring log. The locations and approximate ground surface elevations of each boring should be considered accurate only to the degree implied by the methods used to make the field measurements. Photographs of the site taken at the time of drilling are provided with this report. The borings were performed using a truck-mounted CME-55 drill rig equipped with a hydraulic head employed in drilling and sampling operations. The boreholes were advanced using 4-inch nominal diameter continuous flight augers. Samples of the subsurface materials encountered were obtained using split-barrel and California barrel sampling procedures in general accordance with ASTM Specifications D1586 and D3550, respectively. In the split-barrel and California barrel sampling procedures, standard sampling spoons are driven into the ground by means of a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the samplers is recorded and is used to estimate the in-situ relative density of cohesionless soils and, to a lesser degree of accuracy, the consistency of cohesive soils and hardness of weathered bedrock. In the California barrel sampling procedure, relatively undisturbed samples are obtained in brass liners. All samples obtained in the field were sealed and returned to the laboratory for further examination, classification and testing. Laboratory moisture content tests were performed on each of the recovered samples. In addition, selected samples were tested for fines content and plasticity by washed sieve analysis and Atterberg limits tests. Swell/consolidation tests were completed on selected samples to evaluate the subgrade materials’ tendency to change volume with variation in moisture content and load. The quantity of water soluble sulfates was determined on select samples to evaluate the risk of sulfate attack on site concrete. Results of the outlined tests are indicated on the attached boring logs and summary sheets. As a part of the testing program, all samples were examined in the laboratory and classified in general accordance with the attached General Notes and the Unified Soil Classification System, based on the sample's texture and plasticity. The estimated group symbol for the Unified Soil Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 3 Classification System is shown on the boring logs and a brief description of that classification system is included with this report. Classification of the bedrock was based on visual and tactual observation of disturbed samples and auger cuttings. Coring and/or petrographic analysis may reveal other rock types. SITE AND SUBSURFACE CONDITIONS The Willox Farm Residential Development parcel is located south of Willox Lane and approximately 1/2-mile west of North College Avenue in Fort Collins, Colorado. The project site is generally undeveloped and situated west of the Hickory Village residential development. Open space is located to the southwest and south of the site with existing farm ground to the northeast. The site is relatively flat with an estimated relief of approximately 5-feet (+/-) from north to south. An EEC field engineer was on-site during drilling to direct the drilling activities and evaluate the subsurface materials encountered. Field descriptions of the materials encountered were based on visual and tactual observation of disturbed samples and auger cuttings. The boring logs included with this report may contain modifications to the field logs based on results of laboratory testing and engineering evaluation. Based on results of the field and laboratory evaluation, subsurface conditions can be generalized as follows. In summary, the subsurface soils encountered in the preliminary test borings generally consisted of a relative shallow depth of overburden slightly cohesive subsoils underlain by a zone of fine to coarse granular subsoils, which extended to the bedrock formation below. Clayey sand, silty, clayey sand and/or sandy lean clay subsoils were encountered in each of the preliminary borings beneath the surficial topsoil/vegetative layer and extended to depths of approximately 3 to 5 feet below existing site grades. Silty sand with gravel with interbedded cobbles at increased depths, was encountered beneath the upper slightly cohesive zone and extended to the bedrock formation below in all borings except for Boring B-3. Auguer refusal was encountered in Boring B-3 within a very dense granular/cobble zone at a depth of approximately 12-1/2 feet below existing site grades. Siltstone/sandstone/claystone bedrock was encountered at depths of approximately 16 to 18 feet below existing site grades and extended to the depths explored. The upper slightly cohesive subsoils were generally dry to moist in-situ, soft to stiff / loose to medium dense, exhibited low to moderate plasticity and low swell potential and a slight tendency to hydro-compact at current moisture and Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 4 density conditions. The granular zone was moist to wet, medium dense to dense and exhibited moderate bearing capacity characteristics. The bedrock formation was generally weathered to moderately hard to hard and/or poorly cemented to cemented with increased depths. The stratification boundaries indicated on the boring logs represent the approximate locations of changes in soil and rock types; in-situ, the transition of materials may be gradual and indistinct. GROUNDWATER OBSERVATIONS Observations were made while drilling and after the completion of drilling to detect the presence and level of groundwater. At the time of drilling groundwater was observed in all of the borings at depths of approximately 3 to 5 feet below the ground surface. The borings were backfilled upon completion, therefore subsequent groundwater measurements were not made. Groundwater measurements provided with this report are indicative of groundwater levels at the locations and at the time the borings/groundwater measurements were completed. Based upon review of U.S. Geological Survey maps (1Hillier, et al, 1983), regional groundwater is expected to be encountered at depths ranging from approximately 5 to 10 feet below the existing ground surface at the project site in unconsolidated alluvial deposits. Perched and/or trapped water may be encountered in more permeable zones in the subgrade soils at times throughout the year. Perched water is commonly encountered in soils immediately overlying less permeable bedrock materials. Fluctuations in ground water levels and in the location and amount of perched water may occur over time depending on variations in hydrologic conditions, irrigation activities on surrounding properties and other conditions not apparent at the time of this report. 1 Hillier, Donald E.; Schneider, Paul A., Jr.; and Hutchinson, E. Carter, 1983, Depth to Water Table (1979) in the Boulder-Fort Collins-Greeley Area, Front Range Urban Corridor, Colorado, United States Geological Survey, Map I-855-I. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 5 ANALYSIS AND RECOMMENDATIONS Swell/Consolidation Test Results Swell/consolidation testing is performed to evaluate the swell or collapse potential of soil or bedrock to assist in determining/evaluating foundation, floor slab and/or pavement design criteria. In the swell/consolidation test, relatively undisturbed samples obtained directly from the California barrel sampler are placed in a laboratory apparatus and inundated with water under a pre-established load. The swell-index is the resulting amount of swell or collapse under the initial loading condition expressed as a percent of the sample’s initial thickness. After the inundation period, additional incremental loads are applied to evaluate swell pressure and/or consolidation. As a part of our laboratory testing, we conducted four (4) swell/consolidation tests on relatively undisturbed soil samples obtained at various intervals/depths on the site. The swell index values for the in-situ soil samples analyzed revealed low swell characteristics as indicated on the attached swell test summaries. The (+) test results indicate the soil materials swell potential characteristics while the (-) test results indicate the soils materials collapse/consolidation potential characteristics when inundated with water. The following table summarizes the swell-consolidation laboratory test results for samples obtained during our field explorations for the subject site. Table I – Laboratory Swell-Consolidation Test Results Boring No. Depth, ft. Material Type Swell Consolidation Test Results In-Situ Moisture Content, % Dry Density, PCF Inundation Pressure, psf Swell Index, % (+/-) B-1 2′ Clayey Sand (SC) 16.3 107 500 (-) 0.4% B-2 2′ Sandy Lean Clay (CL) 13.6 113.2 500 (+) 2.0% B-6 2′ Sandy Lean Clay (CL) 22.7 103.2 500 (-) 0.2% B-7 4′ Silty, Clayey Sand (SC-SM) 4.3 122.9 500 (-) 0.5% The Colorado Association of Geotechnical Engineers (CAGE) uses the following information to provide uniformity in terminology between geotechnical engineers to provide a relative correlation risk performance to measured swell. “The representative percent swell values are not necessarily measured values; rather, they are a judgment of the swell of the soil and/or bedrock profile likely to influence Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 6 slab performance.” Geotechnical engineers use this information to also evaluate the swell potential risks for foundation performance based on the risk categories. Table II - Recommended Representative Swell Potential Descriptions and Corresponding Slab Performance Risk Categories Slab Performance Risk Category Representative Percent Swell (500 psf Surcharge) Representative Percent Swell (1000 psf Surcharge) Low 0 to < 3 0 < 2 Moderate 3 to < 5 2 to < 4 High 5 to < 8 4 to < 6 Very High > 8 > 6 Based on the laboratory test results, the samples of overburden subsoils analyzed ranged from non- expansive to low. Additionally, a couple of areas showed soft/compressible characteristics nearing the groundwater table. General Considerations General guidelines are provided below for the site subgrade preparation. However, it should be noted that for possible residential development, compaction and moisture requirements vary between home builders and, consequently, between geotechnical engineering companies. If the residential development lots will be marketed to a target group of builders, fill placement criteria should be obtained from those builders and/or their geotechnical engineering consultants prior to beginning earthwork activities on the site. Representatives from those entities should verify that the fill is being placed consistent with the home builders’ guidelines. The near surface soils varied in moisture and density conditions at the time of drilling and generally exhibited low swell potential characteristics, and soft/compressible characteristics nearing the groundwater table in some of the borings. The presence of bedrock was identified in the soil borings extended within the proposed development area as previously discussed. The presence of bedrock throughout the site should be thoroughly evaluated prior to construction activities commencing. It is likely that individual builders’ geotechnical engineering representatives will require a minimum separation that should be maintained between the bottom of any potential footing foundations and/or floor slabs and bedrock. If the overburden soils or underlying bedrock were to become wetted Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 7 subsequent to construction of overlying improvements, heaving, consolidation, and/or differential heaving caused by soils/underlying bedrock could result in significant total and differential movement of site improvements. Therefore, in areas where shallow bedrock was encountered, consideration could be given to the use of a straight shaft drilled pier foundation system and a structural floor slab system. In addition, with the acceptance of greater risk for movement, preliminary considerations and/or recommendations for an over-excavation and replacement concept to reduce the potential movement of foundations, floor slabs, and pavements, are included herein. Specific methods of reducing the potential for movement are to be determined by the individual/lot- specific builder. Groundwater was encountered at shallow depths in the preliminary soil borings. If lower level construction or full-depth basements are being considered for the site, we would suggest that the lower level subgrade(s) be placed a minimum of 3 feet above the maximum anticipated rise in groundwater levels, or a combination exterior and interior perimeter drainage system(s) be installed in areas with shallow groundwater. Also, consideration could be given to 1) either designing and installing an area underdrain system to lower the groundwater levels provided a gravity discharge point can be established. If a gravity outlet/system cannot be designed another consideration would be to design and install a mechanical sump pump system to discharge the collected groundwater within the underdrain system, or 2) elevate/raise the site grades to establish the minimum suggested 3-foot separation to the maximum anticipated rise in groundwater. Site Preparation All existing vegetation and/or topsoil should be removed from beneath site fills, roadways or building subgrade areas. Stripping depths should be expected to vary, depending, in part, on past agricultural activities. In addition, any soft/loose native soils or any existing fill materials without documentation of controlled fill placement should be removed from improvement and/or new fill areas. Due to the soft/compressible conditions nearing the ground water table, in some areas of the site overburden cohesive subsoils and necessary separation between floor slabs and/or footings and bedrock we recommend following the over-excavation procedures outlined for each respective Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 8 foundation system option, as well as for floor slabs/exterior flatwork and pavements in the sections below. After stripping and completing all cuts, any overexcavation, and prior to placement of any fill, floor slabs or pavements, we recommend the exposed soils be scarified to a minimum depth of 9 inches, adjusted in moisture content and compacted to at least 95% of the material's maximum dry density as determined in accordance with ASTM Specification D698, the standard Proctor procedure. The moisture content of the scarified materials should be adjusted to be within a range of ±2% of standard Proctor optimum moisture at the time of compaction. In general, fill materials required to develop the building areas or site pavement subgrades should consist of approved, low-volume change materials which are free from organic matter and debris. The approved imported structural fill or with the understanding of greater potential for movement, the site lean clay soils could be used as fill in these areas. If granular imported structural fill is used, it should be similar to CDOT Class 5, 6 or 7 base course material with sufficient fines to prevent ponding of water in the fill. The claystone bedrock should not be used for fill in site improvement areas. We recommend the fill soils be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content and compacted to at least 95% of the material’s maximum dry density as determined in accordance with the standard Proctor procedure. The moisture content of predominately clay soils should be adjusted to be within the range of ±2% of optimum moisture content at the time of placement. Granular soil should be adjusted to a workable moisture content. Specific explorations should be completed for each building/individual lot to develop recommendations specific to the proposed structure and owner/builder and for specific pavement sections. A greater or lesser degree of compaction could be specified for specific individual structures along with alternative moisture requirements. The preliminary recommendations provided in this report are, by necessity, general in nature and would be superseded by site specific explorations/recommendations. Care should be taken after preparation of the subgrades to avoid disturbing the subgrade materials. Positive drainage should be developed away from structures and across and away from pavement edges to avoid wetting of subgrade materials. Subgrade materials allowed to become wetted Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 9 subsequent to construction of the residences and/or pavements can result in unacceptable performance of those improvements. Foundation Systems – General Considerations The cohesive subsoils will require particular attention in the design and construction to reduce the amount of movement due to the in-situ soft/compressible characteristics. Groundwater was also encountered at relatively shallow depths across the site which will require special attention in the overall design and construction of the project. As previously mentioned, consideration could be given to the installation of an area underdrain system. The following foundation systems were evaluated for use on the site; however final subsurface explorations should be performed after building footprints and elevations have been better defined and actual design loads determined:  Conventional type spread footings bearing on native subsoils or engineered controlled fill material, and  Grade beams and straight shaft piers/caissons drilled into the bedrock Other alternative foundation systems could be considered, and we would be pleased to provide additional alternatives upon request. Preliminary Spread Footing Foundation Recommendations We anticipate use of conventional footing foundations could be considered for lightly loaded structures at this site. We expect footing foundations would be supported either on the native soils or on newly placed and compacted fills. Soft and/or loose zones were observed in the near surface sandy clay soils so that care will be necessary to see that foundations are not supported directly on soft or loose materials. Mitigation for soft subgrade soils should be expected over much of the site. Additionally, a separation between the bedrock and the building footings should be maintained. Certain residential home builders may also have a specified separation from bottom of footings to the underlying bedrock formation. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 10 In areas where the cohesive subsoils exhibited elevated moisture contents near and/or encroaching the groundwater levels and/or where relatively low SPT N-Blows/ft. were recorded indicating “soft soils” we would expect these soft zones would require particular attention/ground modification procedures to develop increased support capacity characteristics. We expect enhancing/stiffening of the subgrade/bearing soils could be accomplished by incorporating into the soft/compressible subsoils a layer granular rock (i.e., 1-½ inches minus crushed concrete aggregate) into the top 12- inches (+/-) of the subgrades as an initial means and method. Depending on the proximity to groundwater and/or severity of the soft soils, overexcavation and backfill with an approved imported structural fill material placed and compacted as outlined herein could also be considered. We suggest an overexcavation and backfill procedure be considered, which would be necessary beneath site structures to reduce the potential for post construction movement. Consideration could be given to a minimum 2-foot overexcavation/backfill procedure beneath site structures in areas where soft soils are expected. After completing a site-specific/lot-specific geotechnical exploration study, a thorough “open-hole/foundation excavation” observation should be performed prior to foundation formwork placement to determine the extent of any over-excavation and replacement procedure. Deeper overexcavation depths may be necessary depending upon the observed subsoils at the time of the foundation excavation observation. In general, the overexcavation area would extend 8 inches laterally beyond the building perimeter for every 12 inches of overexcavation depth. We anticipate backfill materials would consist of an approved imported granular structural fill material such as a CDOT Class 7 aggregate base course (ABC) either native and/or recycled concrete oriented and/or equivalent, which is placed in uniforms lifts, properly adjusted in moisture content and mechanically compacted to at least 97% of the material’s Standard Proctor Density (ASTM D698) results. For design of footing foundations bearing on approved native subsoils, (i.e., the native subsoils in which soft/compressible conditions are not encountered), or on properly placed and compacted fill materials as outlined above, maximum net allowable total load soil bearing pressures on the order of 1,500 to 2,500 psf could be considered depending upon the specific backfill material used. Footing foundations should maintain separation above maximum anticipated rise in groundwater elevation of at least 4 feet indicated earlier. The net bearing pressure refers to the pressure at foundation bearing level in excess of the minimum surrounding overburden pressure. Total load would include full dead and live loads. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 11 Exterior foundations and foundations in unheated areas are typically located at least 30 inches below adjacent exterior grade to provide frost protection. Formed continuous footings would have minimum widths of 12 to 16 inches and isolated column foundations would have a minimum width of 24 to 30 inches. Trenched foundations or grade beam foundations could probably be used in the near surface soils. If used, trenched foundations would have a minimum width of 12 inches and formed continuous foundations a minimum width of 8 inches. Care should be taken to avoid placement of structures partly on native soils and partly on newly placed fill materials. In these areas, mitigation approaches could include surcharging of the fill materials, overexcavation of the native soils or use of alternative foundations, such as drilled piers, along with structural floors. Mitigation approaches may vary between structures depending, in part, on the extent and depth of new fill placement. Specific approaches could be established at the time of exploration for the individual structures. Care should be taken on the site to fully document the horizontal and vertical extent of fill placement on the site, including benching the fill into native slopes. Preliminary Drilled Pier Foundations Depending upon the final grades and/or the acceptable tolerances of potential movement, another alternative foundation system would be to support the residential structures on a grade beam and straight shaft drilled pier/caisson foundation system. Drilled piers would develop support capacity through end bearing and skin friction in the bedrock underlying the site. The design parameters for the drilled pier foundations would need to be developed in the specific structure areas due to the variable nature of the subsurface materials observed across the site. Drilled piers typically extend into the weathered claystone bedrock on the order of approximately 10 to 15 feet or to a minimum length of 25 feet or greater whichever results in the longer drilled pier. For design of drilled pier foundations bearing in the moderately hard weathered claystone bedrock, we anticipate total load end bearing pressures on the order of approximately 30,000 psf could be used along with a skin friction value of 3,000 psf. Minimum dead load pressures would likely be required on drilled pier foundations bearing on claystone bedrock. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 12 We anticipate temporary casing will be needed to prevent sloughing of soil and/or flow of groundwater into the pier excavations. Concrete placed in the drilled piers should have a slump in the range of 5 to 8 inches to promote complete filling of the drilled shaft excavation. Preliminary Basement Design and Construction Groundwater was encountered across the site within some of the preliminary soil borings at depths of approximately 3 to 5 feet below existing site grades. If lower level construction for either garden- level or full-depth basements is being considered for the site, we would suggest that the lower level subgrade(s) be placed a minimum of 3 feet above maximum anticipated rise in groundwater levels, or a combination exterior and interior perimeter drainage system(s) be installed in areas with shallow groundwater. For each individual building with a garden level or full-depth basement located less than 3 feet above maximum groundwater levels, the dewatering system should, at a minimum, include an under- slab gravel drainage layer sloped to an interior perimeter drainage system. Considerations for the preliminary design of the combination exterior and interior perimeter drainage system are as follows: The under-slab drainage system should consist of a properly sized perforated pipe, embedded in free- draining gravel, placed in a trench at least 12 inches in width. The trench should be inset from the interior edge of the nearest foundation a minimum of 12 inches. In addition, the trench should be located such that an imaginary line extending downward at a 45-degree angle from the foundation does not intersect the nearest edge of the trench. Gravel should extend a minimum of 3 inches beneath the bottom of the pipe. The underslab drainage system should be sloped at a minimum 1/8 inch per foot to a suitable outlet, such as a sump and pump system. The underslab drainage layer should consist of a minimum 6-inch thickness of free-draining gravel meeting the specifications of ASTM C33, Size No. 57 or 67 or equivalent. Cross-connecting drainage pipes should be provided beneath the slab at minimum 15-foot intervals and should discharge to the perimeter drainage system. Sizing of drainage pipe will be dependent upon groundwater flow into the dewatering system. Groundwater flow rates will fluctuate with permeability of the soils to be dewatered and the depth to Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 13 which groundwater may rise in the future. Pump tests to determine groundwater flow rates are recommended in order to properly design the system. For preliminary design purposes, the drainage pipe, sump and pump system should be sized for a projected flow of 0.5 x 10-3 cubic feet per second (cfs) per lineal foot of drainage pipe. Additional recommendations can be provided upon request and should be presented in final subsurface exploration reports for each residential lot. The exterior drainage system should be constructed around the exterior perimeter of the lower level/below grade foundation system and sloped at a minimum 1/8 inch per foot to a suitable outlet, such as a sump and pump system. The exterior drainage system should consist of a properly sized perforated pipe, embedded in free- draining gravel, placed in a trench at least 12 inches in width. Gravel should extend a minimum of 3 inches beneath the bottom of the pipe, and at least 2 feet above the bottom of the foundation wall. The system should be underlain with a polyethylene moisture barrier, sealed to the foundation walls, and extended at least to the edge of the backfill zone. The gravel should be covered with drainage fabric prior to placement of foundation backfill. Preliminary Floor Slab/Exterior Flatwork Subgrades We recommend all existing vegetation/topsoil be removed from beneath the floor slab and exterior flatwork areas as previously outlined. After stripping and completing all cuts and prior to placement of any flatwork concrete or fill, the exposed subgrades should be scarified, adjusted in moisture content and compacted. If the subgrades become dry and desiccated prior to floor slab construction, it may be necessary to rework the subgrades prior to floor slab placement. Fill soils required to develop the floor slab subgrades should consist of approved, low-volume change materials which are free from organic matter and debris. Those fill materials should be placed as previously outlined and surcharged/preloaded and/or monitored as necessary to limit total and differential movement after construction of overlying improvements. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 14 Lateral Earth Pressures Any site retaining walls or similarly related structural elements that would be subjected to unbalanced lateral earth pressures would also be subjected to lateral soil forces. Passive lateral earth pressures may help resist the driving forces for retaining wall or other similar site structures. Active lateral earth pressures could be used for design of structures where some movement of the structure is anticipated, such as retaining walls. The total deflection of structures for design with active earth pressure is estimated to be on the order of one half of one percent of the height of the down slope side of the structure. We recommend at-rest pressures be used for design of structures where rotation of the walls is restrained, including the grade beam walls for the loading docks. Free standing wing walls could be designed for active pressures assuming rotation of the walls is allowed. Passive pressures and friction between the footing and bearing soils could be used for design of resistance to movement of retaining walls. Coefficient values for backfill with anticipated types of soils for calculation of active, at rest and passive earth pressures are provided in Table III below. Equivalent fluid pressure is equal to the coefficient times the appropriate soil unit weight. Those coefficient values are based on horizontal backfill with backfill soils consisting of essentially granular materials or low volume change cohesive soils. For the at-rest and active earth pressures, slopes down and away from the structure would result in reduced driving forces with slopes up and away from the structures resulting in greater forces on the walls. The passive resistance would be reduced with slopes away from the wall. The top 30 inches of soil on the passive resistance side of walls could be used as a surcharge load; however, should not be used as a part of the passive resistance value. Frictional resistance is equal to the tangent of the friction angle times the normal force. Surcharge loads or point loads placed in the backfill can also create additional loads on below grade walls. Those situations should be designed on an individual basis. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 15 Table III Parameters for Lateral Earth Pressures Soil Type Clayey Sand / Sandy Lean Clay Granular Subsoils Wet Unit Weight 115 135 Saturated Unit Weight 135 145 Friction Angle, f (assumed) 25° 35° Active Pressure Coefficient 0.40 0.27 At-rest Pressure Coefficient 0.58 0.42 Passive Pressure Coefficient 2.46 3.69 The outlined values do not include factors of safety nor allowances for hydrostatic loads and are based on assumed friction angles, which should be verified after potential material sources have been identified. The outlined values assume wall backfill consists of non-expansive material extending a minimum distance of 4 feet laterally away from all walls. Care should be taken to develop appropriate drainage systems behind below grade walls to reduce potential for hydrostatic loads developing on the walls and infiltration of water into below grade areas. Those systems would likely include perimeter drain systems extending to sump areas or free outfall where reverse flow cannot occur into the system. Where necessary, appropriate hydrostatic load values should be used for design. Preliminary Pavement Subgrades Based on the current subsurface conditions, we believe pavements could be placed directly on properly prepared native subsoils and/or structural fill material. Pavement subgrades should be prepared as described in the section site preparation. After completion of the pavement subgrades, care should be taken to prevent disturbance of those materials prior to placement of the overlying pavements. Soils which are disturbed by construction activities should be reworked in-place or, if necessary, removed and replaced prior to placement of overlying fill or pavements. Depending on final site grading and/or weather conditions at the time of pavement construction, stabilization of a portion of the site pavement subgrades may be required to develop suitable Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 16 pavement subgrades. The site clayey soils could be subject to instability at higher moisture contents. Stabilization could also be considered as part of the pavement design, although prior to finalizing those sections, a stabilization mix design would be required. Preliminary Site Pavements Pavement sections are based on traffic volumes and subgrade strength characteristics. An assumed R-Value of 10 was used for the preliminary pavement design. Suggested preliminary pavement sections for the local residential and minor collector roadways are provided below in Table IV. Thicker pavement sections may be required for roadways classified as major collectors. A final pavement design thickness evaluation will be determined when a pavement design exploration is completed (after subgrades are developed to ± 6 inches of design and wet utilities installed in the roadways). The projected traffic may vary from the traffic assumed from the roadway classification based on a site-specific traffic study. TABLE IV – PRELIMINARY MINIMUM PAVEMENT THICKNESS SECTIONS Local Residential Roadways Minor Collectors Roadways EDLA – assume local residential roadways Reliability Resilient Modulus PSI Loss – (Initial 4.5, Terminal 2.0 and 2.5 respectively) 10 75% 3562 2.5 25 80% 3562 2.2 Design Structure Number 2.67 3.11 Composite Section without Fly Ash – Alternative A Hot Mix Asphalt (HMA) Grading S (75) PG 58-28 Aggregate Base Course ABC – CDOT Class 5 or 6 Design Structure Number 4ʺ 9ʺ (2.75) 5ʺ 9ʺ (3.19) Composite Section with Fly Ash – Alternative B Hot Mix Asphalt (HMA) Grading S (75) PG 58-28 Aggregate Base Course ABC – CDOT Class 5 or 6 Fly Ash Treated Subgrade Design Structure Number 4ʺ 6 ʺ 12″ (2.92) 4ʺ 7ʺ 12ʺ (3.04) PCC (Non-reinforced) – placed on an approved subgrade 6″ 6½″ Asphalt surfacing should consist of grading S-75 or SX-75 hot bituminous pavement with PG 64-22 or PG 58-28 binder in accordance with Larimer County requirements. Aggregate base should be consistent with CDOT requirements for Class 5 or Class 6 aggregate base. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 17 As previously mentioned, a final subgrade investigation and pavement design should be performed in general accordance with the Larimer County Urban Area Street Standards (LCUASS) prior to placement of any pavement sections, to determine the required pavement section after design configurations, roadway utilities have been installed and roadway have been prepared to “rough” subgrade elevations have been completed. Underground Utility Systems All piping should be adequately bedded for proper load distribution. It is suggested that clean, graded gravel compacted to 70 percent of Relative Density ASTM D4253 be used as bedding. Utility trenches should be excavated on safe and stable slopes in accordance with OSHA regulations as further discussed herein. Backfill should consist of the on-site soils or approved imported materials. The pipe backfill should be compacted to a minimum of 95 percent of Standard Proctor Density ASTM D698. Water Soluble Sulfates (SO4) The water-soluble sulfate (SO4) content of the on-site overburden subsoils, taken during our subsurface exploration at random locations and intervals are provided below. Based on reported sulfate content test results, the Class/severity of sulfate exposure for concrete in contact with the on- site subsoils is provided in this report. Table V: Water Soluble Sulfate Test Results Sample Location Description Soluble Sulfate Content % B-6, S-2, at 4’ Clayey Sand (SC) / Sandy Lean Clay (CL) 0.01 Based on the results as presented above, ACI 318, Section 4.2 indicates the site lean clay soils a low risk of sulfate attack on Portland cement concrete, therefore, ACI Class S0 requirements should be followed for concrete placed in the overburden soils and underlying bedrock. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 18 Other Considerations and Recommendations Although evidence of fills or underground facilities such as septic tanks, cesspools, and basements was not observed during the site reconnaissance, such features could be encountered during construction. If unexpected fills or underground facilities are encountered, such features should be removed, and the excavation thoroughly cleaned prior to backfill placement and/or construction. Excavations into the lean clay soils and bedrock can be expected to stand on relatively steep temporary slopes during construction. The individual contractor(s) should be made responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom. All excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. GENERAL COMMENTS The analysis and recommendations presented in this report are based upon the data obtained from the soil borings performed at the indicated locations and from any other information discussed in this report. This report does not reflect any variations which may occur between borings or across the site. The nature and extent of such variations may not become evident until construction. If variations appear evident, it will be necessary to re-evaluate the recommendations of this report. Site specific explorations will be necessary for the proposed site buildings. It is recommended that the geotechnical engineer be retained to review the plans and specifications so that comments can be made regarding the interpretation and implementation of our geotechnical recommendations in the design and specifications. It is further recommended that the geotechnical engineer be retained for testing and observations during earthwork and foundation construction phases to help determine that the design requirements are fulfilled. This report has been prepared for the exclusive use of Mosaic Land Development Services, LLC for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranty, express or implied, is made. In the event that any changes in the nature, design or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Earth Engineering Consultants, LLC EEC Project No. 1212027 May 6, 2021 Page 19 the changes are reviewed, and the conclusions of this report modified or verified in writing by the geotechnical engineer. Earth Engineering Consultants, LLC DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS: SS: Split Spoon ‐ 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample ST: Thin‐Walled Tube ‐ 2" O.D., unless otherwise noted WS: Wash Sample R: Ring Barrel Sampler ‐ 2.42" I.D., 3" O.D. unless otherwise noted PA: Power Auger FT: Fish Tail Bit HA: Hand Auger RB: Rock Bit DB: Diamond Bit = 4", N, B BS: Bulk Sample AS: Auger Sample PM: Pressure Meter HS: Hollow Stem Auger WB: Wash Bore Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2‐inch O.D. split spoon, except where noted. WATER LEVEL MEASUREMENT SYMBOLS: WL : Water Level WS : While Sampling WCI: Wet Cave in WD : While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB : After Boring ACR: After Casting Removal Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated levels may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not possible with only short term observations. DESCRIPTIVE SOIL CLASSIFICATION Soil Classification is based on the Unified Soil Classification system and the ASTM Designations D‐2488. Coarse Grained Soils have move than 50% of their dry weight retained on a #200 sieve; they are described as: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are described as : clays, if they are plastic, and silts if they are slightly plastic or non‐plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse grained soils are defined on the basis of their relative in‐ place density and fine grained soils on the basis of their consistency. Example: Lean clay with sand, trace gravel, stiff (CL); silty sand, trace gravel, medium dense (SM). CONSISTENCY OF FINE‐GRAINED SOILS Unconfined Compressive Strength, Qu, psf Consistency < 500 Very Soft 500 ‐ 1,000 Soft 1,001 ‐ 2,000 Medium 2,001 ‐ 4,000 Stiff 4,001 ‐ 8,000 Very Stiff 8,001 ‐ 16,000 Very Hard RELATIVE DENSITY OF COARSE‐GRAINED SOILS: N‐Blows/ft Relative Density 0‐3 Very Loose 4‐9 Loose 10‐29 Medium Dense 30‐49 Dense 50‐80 Very Dense 80 + Extremely Dense PHYSICAL PROPERTIES OF BEDROCK DEGREE OF WEATHERING: Slight Slight decomposition of parent material on joints. May be color change. Moderate Some decomposition and color change throughout. High Rock highly decomposed, may be extremely broken. HARDNESS AND DEGREE OF CEMENTATION: Limestone and Dolomite: Hard Difficult to scratch with knife. Moderately Can be scratched easily with knife. Hard Cannot be scratched with fingernail. Soft Can be scratched with fingernail. Shale, Siltstone and Claystone: Hard Can be scratched easily with knife, cannot be scratched with fingernail. Moderately Can be scratched with fingernail. Hard Soft Can be easily dented but not molded with fingers. Sandstone and Conglomerate: Well Capable of scratching a knife blade. Cemented Cemented Can be scratched with knife. Poorly Can be broken apart easily with fingers. Cemented Group Symbol Group Name Cu≥4 and 1<Cc≤3E GW Well-graded gravel F Cu<4 and/or 1>Cc>3E GP Poorly-graded gravel F Fines classify as ML or MH GM Silty gravel G,H Fines Classify as CL or CH GC Clayey Gravel F,G,H Cu≥6 and 1<Cc≤3E SW Well-graded sand I Cu<6 and/or 1>Cc>3E SP Poorly-graded sand I Fines classify as ML or MH SM Silty sand G,H,I Fines classify as CL or CH SC Clayey sand G,H,I inorganic PI>7 and plots on or above "A" Line CL Lean clay K,L,M PI<4 or plots below "A" Line ML Silt K,L,M organic Liquid Limit - oven dried Organic clay K,L,M,N Liquid Limit - not dried Organic silt K,L,M,O inorganic PI plots on or above "A" Line CH Fat clay K,L,M PI plots below "A" Line MH Elastic Silt K,L,M organic Liquid Limit - oven dried Organic clay K,L,M,P Liquid Limit - not dried Organic silt K,L,M,O Highly organic soils PT Peat (D30)2 D10 x D60 GW-GM well graded gravel with silt NPI≥4 and plots on or above "A" line. GW-GC well-graded gravel with clay OPI≤4 or plots below "A" line. GP-GM poorly-graded gravel with silt PPI plots on or above "A" line. GP-GC poorly-graded gravel with clay QPI plots below "A" line. SW-SM well-graded sand with silt SW-SC well-graded sand with clay SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay Earth Engineering Consultants, LLC IIf soil contains >15% gravel, add "with gravel" to group name JIf Atterberg limits plots shaded area, soil is a CL- ML, Silty clay Unified Soil Classification System Soil Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests Sands 50% or more coarse fraction passes No. 4 sieve Fine-Grained Soils 50% or more passes the No. 200 sieve <0.75 OL Gravels with Fines more than 12% fines Clean Sands Less than 5% fines Sands with Fines more than 12% fines Clean Gravels Less than 5% fines Gravels more than 50% of coarse fraction retained on No. 4 sieve Coarse - Grained Soils more than 50% retained on No. 200 sieve CGravels with 5 to 12% fines required dual symbols: Kif soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel", whichever is predominant. <0.75 OH Primarily organic matter, dark in color, and organic odor ABased on the material passing the 3-in. (75-mm) sieve ECu=D60/D10 Cc= HIf fines are organic, add "with organic fines" to group name LIf soil contains ≥ 30% plus No. 200 predominantly sand, add "sandy" to group name. MIf soil contains ≥30% plus No. 200 predominantly gravel, add "gravelly" to group name. DSands with 5 to 12% fines require dual symbols: BIf field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name.FIf soil contains ≥15% sand, add "with sand" to GIf fines classify as CL-ML, use dual symbol GC- CM, or SC-SM. Silts and Clays Liquid Limit less than 50 Silts and Clays Liquid Limit 50 or more 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100 110 PL A S T I C I T Y I N D E X ( P I ) LIQUID LIMIT (LL) ML OR OL MH OR OH For Classification of fine-grained soils and fine-grained fraction of coarse-grained soils. Equation of "A"-line Horizontal at PI=4 to LL=25.5 then PI-0.73 (LL-20) Equation of "U"-line Vertical at LL=16 to PI-7, then PI=0.9 (LL-8) CL-ML WILLOX FARM FORT COLLINS, COLORADO EEC PROJECT NO. 1212027 APRIL 2021 B-1 B-2 B-3 B-4 B-5 B-6 B-7 1 2 Figure 1 - Boring Location Diagram Willox Farms Fort Collins, Colorado EEC Project #: 1212027 Date: April 2021 Approximate Boring Locations 1 EARTH ENGINEERING CONSULTANTS, LLC Legend Site PKotos PKotos taNen in approximate location, in direction oI arroZ B-1 B-2 B-3 B-4 B-5 B-6 B-7 Approximate Boring Locations Ior 7 Preliminar\ Borings, 1 - 2 EARTH ENGINEERING CONSULTANTS, LLC Legend Figure 2 - Boring Location Diagram Willox Farms Fort Collins, Colorado EEC Project #: 1212027 Date: April 2021 DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 CLAYEY SAND (SC) _ _ brown, loose to medium dense 2 _ _ CS 3 3 500 16.3 112.7 27 9 31.1 <500 None _ _ 4 _ _ SS 5 12 --- 22.4 _ _ SAND / GRAVEL (SP / GP) 6 gray, rust, moist to wet, medium dense to dense _ _ 7 _ _ 8 *classified as WELL GRADED SAND with GRAVEL _ _ 9 with cobbles _ _ CS 10 50/9" --- 8.3 146.1 0.2 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ SS 15 50/9.5" --- 15.5 _ _ 16 _ _ SILTSTONE/CLAYSTONE/SANDSTONE 17 brown/gray/rust, poorly to well cemented CS _ _50/6.5" 9000+ 14.1 119.7 18 *auger refusal with cemented SANDSTONE lens _ _ 19 BOTTOM OF BORING DEPTH 19.0' _ _ 20 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC WILLOX FARMS FORT COLLINS, COLORADO LOG OF BORING B-1PROJECT NO: 1212027 APRIL 2021 SHEET 1 OF 1 WATER DEPTH START DATE 4/21/2021 WHILE DRILLING 5' APPROX. SURFACE ELEV 4987 FINISH DATE 4/21/2021 AFTER DRILLING 3' A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 SANDY LEAN CLAY (CL) _ _ dark brown, medium stiff to stiff 2 _ _ CS 3 14 4000 13.6 103.4 3500 (+) 2.0 _ _ 4 _ _ SILTY SAND with GRAVEL (SM) SS 5 16 --- 9.6 0.6 gray, rust, moist to wet, medium dense _ _ 6 *classified as POORLY GRADED SAND with GRAVEL _ _ 7 _ _ 8 _ _ 9 _ _ SS 10 17 --- 20.5 _ _ with cobble 11 _ _ 12 _ _ 13 _ _ 14 _ _ 15 _ _ 16 _ _ SILTSTONE/CLAYSTONE/SANDSTONE 17 brown/gray/rust, poorly to well cemented _ _ 18 _ _ 19 *auger refusal within cemented sandstone lense _ _ AC 20 18.5 BOTTOM OF BORING DEPTH 19.0' _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC WILLOX FARMS FORT COLLINS, COLORADO PROJECT NO: 1212027 LOG OF BORING B-2 APRIL 2021 SHEET 1 OF 1 WATER DEPTH START DATE 4/21/2021 WHILE DRILLING 4.5' APPROX. SURFACE ELEV 4986 FINISH DATE 4/21/2021 Auger Cuttings - AC A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF _ _ CLAYEY SAND (SC) / SANDY LEAN CLAY (CL) 1 brown, moist, medium stiff / medium dense _ _ 2 _ _ 3 _ _ SILTY SAND with GRAVEL (SM) 4 gray, rust, moist to wet, medium dense _ _ CS 5 44 --- _ _ 6 _ _ 7 _ _ with cobbles 8 _ _ 9 _ _ *classified as WELL GRADED SAND with GRAVEL SS 10 50 --- 9.2 0.5 _ _ 11 _ _ *Auger refusal on very dense cobble zone 12 BOTTOM OF BORING DEPTH 12' _ _ 13 _ _ 14 _ _ 15 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ 20 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC WILLOX FARMS FORT COLLINS, COLORADO PROJECT NO: 1212027 LOG OF BORING B-3 APRIL 2021 SHEET 1 OF 1 WATER DEPTH START DATE 4/21/2021 WHILE DRILLING 4' APPROX. SURFACE ELEV 4986 FINISH DATE 4/21/2021 A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 CLAYEY SAND (SC) / SANDY LEAN CLAY (CL) _ _ brown, loose / soft 2 _ _ 3 _ _ 4 _ _ SILTY SAND with GRAVEL (SM) CS 5 1 --- 19.4 gray, rust, moist to wet, loose to medium dense to dense _ _ 6 _ _ 7 with cobbles _ _ 8 _ _ 9 _ _ *classified as POORLY GRADED SAND w/ GRAVEL SS 10 40 --- 11.4 0.6 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ SS 15 50/9" --- 13.2 _ _ 16 _ _ 17 _ _ 18 _ _ SILTSTONE/CLAYSTONE/SANDSTONE 19 brown/gray/rust, poorly to well cemented _ _ CS 20 50/6" 9000+ 15.4 115.8 BOTTOM OF BORING DEPTH 20' _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC WILLOX FARMS FORT COLLINS, COLORADO PROJECT NO: 1212027 LOG OF BORING B-4 APRIL 2021 SHEET 1 OF 1 WATER DEPTH START DATE 4/21/2021 WHILE DRILLING 4.5' APPROX. SURFACE ELEV 4984 FINISH DATE 4/21/2021 A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 SANDY LEAN CLAY (CL) _ _ brown, moist to wet, very soft 2 _ _ CS 3 2 1000 26.1 _ _ 4 _ _ SS 5 1 34.7 _ _ 6 SILTY SAND with GRAVEL (SM) _ _ gray, rust, moist to wet, medium dense to dense 7 _ _ 8 _ _ with cobbles 9 _ _ 10 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ 15 _ _ 16 _ _ 17 _ _ SILTSTONE/SANDSTONE/CLAYSTONE 18 brown/gray/rust, moderately hard to hard _ _ AC 19 19.5 BOTTOM OF BORING DEPTH 19' _ _ 20 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC WILLOX FARMS FORT COLLINS, COLORADO PROJECT NO: 1212027 LOG OF BORING B-5 APRIL 2021 SHEET 1 OF 1 WATER DEPTH START DATE 4/21/2021 WHILE DRILLING 5' APPROX. SURFACE ELEV 4984 FINISH DATE 4/21/2021 Auger Cuttings A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 SANDY LEAN CLAY (CL) _ _ brown, medium stiff to stiff 2 _ _ CS 3 7 2500 22.7 101.4 30 10 60.9 <500 None _ _ 4 _ _ SS 5 22 --- 12.4 _ _ SILTY SAND with GRAVEL (SM) 6 gray, rust, moist to wet, medium dense to dense _ _ 7 _ _ with cobbles 8 _ _ 9 _ _ *classified as POORLY GRADED SAND w/ GRAVEL SS 10 29 --- 9.1 0.5 _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ SS 15 50/9" --- 19.2 _ _ 16 _ _ 17 _ _ 18 _ _ SILTSTONE/SANDSTONE/CLAYSTONE 19 brown/gray/rust, moderately hard to hard _ _ *classified as SANDY LEANCLAY SS 20 50/7" 6500 18.5 32 12 54.1 _ _ BOTTOM OF BORING DEPTH 20.5' 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC WILLOX FARMS FORT COLLINS, COLORADO PROJECT NO: 1212027 LOG OF BORING B-6 APRIL 2021 SHEET 1 OF 1 WATER DEPTH START DATE 4/21/2021 WHILE DRILLING 5' APPROX. SURFACE ELEV 4983 FINISH DATE 4/21/2021 A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 CLAYEY SAND (SC) / SANDY LEAN CLAY (CL) _ _ brown, moist, medium stiff / medium dense to stiff 2 _ _ 3 _ _ 4 _ _ SILTY SAND with GRAVEL (SM) CS 5 30 --- 4.3 117.0 <500 None gray, rust, moist to wet, medium dense to dense _ _ 6 _ _ with cobbles 7 _ _ 8 _ _ 9 _ _ SS 10 48 --- 10.9 _ _ 11 _ _ 12 _ _ 13 _ _ 14 SS _ _50/8" 1500 17.1 15 _ _ 16 _ _ 17 _ _ SILTSTONE/SANDSTONE/CLAYSTONE 18 brown/gray/rust, moderately hard to hard _ _ 19 _ _ 20 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ AC 25 BOTTOM OF BORING DEPTH 24.0' _ _ Earth Engineering Consultants, LLC WILLOX FARMS FORT COLLINS, COLORADO PROJECT NO: 1212027 LOG OF BORING B-7 APRIL 2021 SHEET 1 OF 1 WATER DEPTH START DATE 4/21/2021 WHILE DRILLING 5' APPROX. SURFACE ELEV 4983 FINISH DATE 4/21/2021 Auger Cuttings - AC A-LIMITS SWELL Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description: brown CLAYEY SAND (SC) Sample Location: Boring 1, Sample 1, Depth 2' Liquid Limit: 27 Plasticity Index: 9 % Passing #200: 31.1% Beginning Moisture: 16.3% Dry Density: 107 pcf Ending Moisture: 17.6% Swell Pressure: <500 psf % Swell @ 500: None Willox Farms Fort Collins, Colorado 1212027 April 2021 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o Water Added Project: Location: Project #: Date: Willox Farms Fort Collins, Colorado 1212027 April 2021 Beginning Moisture: 13.6% Dry Density: 113.2 pcf Ending Moisture: 16.7% Swell Pressure: 3500 psf % Swell @ 500: 2.0% Sample Location: Boring 2, Sample 1, Depth 2' Liquid Limit: - - Plasticity Index: - - % Passing #200: - - SWELL / CONSOLIDATION TEST RESULTS Material Description: brown CLAYEY SAND (SC) / SANDY LEAN CLAY (CL) -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o Water Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description: brown SANDY LEAN CLAY (CL) Sample Location: Boring 6, Sample 1, Depth 2' Liquid Limit: 30 Plasticity Index: 10 % Passing #200: 60.9% Beginning Moisture: 22.7% Dry Density: 103.2 pcf Ending Moisture: 20.7% Swell Pressure: < 500 psf % Swell @ 500: None Willox Farms Fort Collins, Colorado 1212027 April 2021 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o Water Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description: brown CLAYEY SAND (SC) / SILTY SAND (SM) Sample Location: Boring 7, Sample 1, Depth 4' Liquid Limit: - - Plasticity Index: - - % Passing #200: - - Beginning Moisture: 4.3% Dry Density: 122.9 pcf Ending Moisture: 3.9% Swell Pressure: < 500 psf % Swell @ 500: None Willox Farms Fort Collins, Colorado 1212027 April 2021 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o Water Added 2 1/2" (63 mm) 2" (50 mm) 1 1/2" (37.5 mm) 1" (25 mm) 3/4" (19 mm) 1/2" (12.5 mm) 3/8" (9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project: Willox Farms Location: Fort Collins, Colorado Project No: 1212027 Sample ID: B1 S3 9 Sample Desc.: Well Graded Sand with Gravel (SW) Date: April 2021 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) 100 Sieve Size Percent Passing 100 100 100 100 78 71 59 42 3 0.2 38 25 14 10 7 1.49 0.41 Fine 12.30 1.07 D30 D10 Cu CC April 2021 19.00 5.05 3.48 Willox Farms Fort Collins, Colorado 1212027 B1 S3 9 Well Graded Sand with Gravel (SW) D100 D60 D50 EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or ClayGravel Coarse Fine Sand Coarse Medium 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 0.010.11101001000 Fi n e r b y W e i g h t ( % ) Grain Size (mm) Standard Sieve Size 2 1/2" (63 mm) 2" (50 mm) 1 1/2" (37.5 mm) 1" (25 mm) 3/4" (19 mm) 1/2" (12.5 mm) 3/8" (9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project: Willox Farms Location: Fort Collins, Colorado Project No: 1212027 Sample ID: B2 S2 4 Sample Desc.: Poorly Graded Sand with Gravel (SP) Date: April 2021 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) 100 Sieve Size Percent Passing 100 100 91 72 62 46 40 35 5 0.6 32 25 17 13 10 1.74 0.31 Fine 39.39 0.82 D30 D10 Cu CC April 2021 37.50 12.11 10.26 Willox Farms Fort Collins, Colorado 1212027 B2 S2 4 Poorly Graded Sand with Gravel (SP) D100 D60 D50 EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or ClayGravel Coarse Fine Sand Coarse Medium 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 0.010.11101001000 Fi n e r b y W e i g h t ( % ) Grain Size (mm) Standard Sieve Size 2 1/2" (63 mm) 2" (50 mm) 1 1/2" (37.5 mm) 1" (25 mm) 3/4" (19 mm) 1/2" (12.5 mm) 3/8" (9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project: Willox Farms Location: Fort Collins, Colorado Project No: 1212027 Sample ID: B3 S2 9 Sample Desc.: Well Graded Sand with Gravel (SW) Date: April 2021 83 74 55 3 0.5 50 30 15 11 8 100 100 88 88 85 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) 100 Sieve Size Percent Passing EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or ClayGravel Coarse Fine Sand Coarse Medium April 2021 37.50 2.95 2.03 Willox Farms Fort Collins, Colorado 1212027 B3 S2 9 Well Graded Sand with Gravel (SW) D100 D60 D50 1.18 0.39 Fine 7.54 1.21 D30 D10 Cu CC 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 0.010.11101001000 Fi n e r b y W e i g h t ( % ) Grain Size (mm) Standard Sieve Size 2 1/2" (63 mm) 2" (50 mm) 1 1/2" (37.5 mm) 1" (25 mm) 3/4" (19 mm) 1/2" (12.5 mm) 3/8" (9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project: Willox Farms Location: Fort Collins, Colorado Project No: 1212027 Sample ID: B4 S2 9 Sample Desc.: Poorly Graded Sand with Gravel (SP) Date: April 2021 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) 100 Sieve Size Percent Passing 100 100 94 79 72 68 57 46 5 0.6 44 36 26 21 14 0.83 0.23 Fine 27.15 0.49 D30 D10 Cu CC April 2021 37.50 6.18 3.21 Willox Farms Fort Collins, Colorado 1212027 B4 S2 9 Poorly Graded Sand with Gravel (SP) D100 D60 D50 EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or ClayGravel Coarse Fine Sand Coarse Medium 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 0.010.11101001000 Fi n e r b y W e i g h t ( % ) Grain Size (mm) Standard Sieve Size 2 1/2" (63 mm) 2" (50 mm) 1 1/2" (37.5 mm) 1" (25 mm) 3/4" (19 mm) 1/2" (12.5 mm) 3/8" (9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project: Willox Farms Location: Fort Collins, Colorado Project No: 1212027 Sample ID: B6 S3 9 Sample Desc.: Poorly Graded Sand with Gravel (SP) Date: April 2021 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) 100 Sieve Size Percent Passing 100 100 82 79 70 66 52 39 5 0.5 37 29 22 17 12 1.27 0.26 Fine 29.40 0.83 D30 D10 Cu CC April 2021 37.50 7.57 4.40 Willox Farms Fort Collins, Colorado 1212027 B6 S3 9 Poorly Graded Sand with Gravel (SP) D100 D60 D50 EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or ClayGravel Coarse Fine Sand Coarse Medium 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 0.010.11101001000 Fi n e r b y W e i g h t ( % ) Grain Size (mm) Standard Sieve Size